Soleniod-operated hydraulic pilot valves have been known and used heretofore in connection with hydraulic machine tools and other hydraulic machinary and apparatus including servo-mechanisms. However, such prior pilot valves have generally been designed to control the hydraulic pressure of a main valve unit or the opening and closing of a main hydraulic valve and none of such solenoid-controlled pilot valves, or main valve units which they have controlled, as far as we are aware, has met the need and demand for the present invention, namely, for a proportional flow control hydraulic valve in which oil or like hydraulic fluid flows through fluid flow passages provided in the body of the valve under control of a solenoid-operated pilot valve device and in which the solenoid operating means for the pilot valve is arranged in an electrical energizing circuit which is under control of a manually operable remote control device, which may be manually operated at a point remote from the location of the new proportional flow control hydraulic valve in or as a part of a hydraulic circuit, machine, apparatus or system, such, for example, as the boom of a mobile aerial truck, or the like, so that the operator thereof may control the hydraulic operating system for the boom and the speed of movement of the boom over a wide range from slow or so-called "inching" speeds to maximum speed while the operator is located on the operator's platform.
The present invention relates to an electrically operated pressure-compensated proportional flow control hydraulic valve and a manually operable remote control device therefor for use in hydraulic systems such as are used in hydraulic machine tools, mobile aerial truck booms, marine hydraulic systems, lifting cranes, earth-handling and earth-moving equipment and machinery, automotive trucks, salt, sand and fertilizer spraying or spreading devices, meter-in and meter-out and by-pass type flow control hydraulic circuits.
The new proportional flow control valve includes a valve body having therein an inlet port through which oil or like hydraulic fluid may flow from a hydraulic pump or the like when the energizing circuit and the operating solenoid for the new valve are deenergized. The valve body also has formed therein a regulated flow outlet port; a by-pass outlet port; a regulated flow passage leading from the inlet port to the regulated flow outlet port; and a by-pass flow passage leading from the inlet port to the by-pass outlet port. The valve body also has a hydraulic flow control valve chamber formed therein which is disposed between the inlet port and the regulated flow outlet port and the by-pass outlet port and the hydraulic flow control valve chamber is adapted to have communication with the regulated flow passage and with the by-pass flow passage. In a preferred form of the invention, a hydraulic flow control valve member is arranged in the hydraulic flow control valve chamber and embodies a group of hydraulic fluid control valve ports for controlling the flow of hydraulic fluid from the by-pass flow passage through the hydraulic flow control valve chamber to the regulated flow passage, and spring biasing means in the hydraulic flow control valve chamber normally urges the hydraulic flow control valve member into position to close the hydraulic flow control valve ports so that when the operating solenoid for the new valve is deenergized the main body or volume of oil or like hydraulic fluid flowing into the inlet port will flow through the by-pass flow passage to the by-pass outlet port from which it may flow to a reservoir or returned to the hydraulic circuit in which the new valve is incorporated, or otherwise used.
The valve body also has a branched auxiliary or pilot flow passage formed therein and one and a first branch of the auxiliary or pilot flow passage leads from the inlet port into the hydraulic flow control valve chamber and through a central bore or passage in the hydraulic flow control valve member separate and apart from the group of hydraulic flow control valve ports therein and maintains a constant pilot flow such, for example, as 0.15 gpm, at a predetermined pressure, such, for example, as 50 psi, against the hydraulic flow control valve member through the hydraulic flow control valve chamber into the regulated flow passage so as to maintain a predetermined constant hydraulic pressure such, for example, as 50 psi, against the action of the spring biasing means on the hydraulic flow control valve member.
The other and second branch of the auxiliary or pilot flow passage leads from the inlet port to the opposite end of the hydraulic flow control valve chamber, and has a pilot valve seat formed therein, and a pilot valve member is movably mounted in the auxiliary or pilot flow passage for movement toward and into engagement with the pilot valve seat.
The movable pilot valve member is under control of an energizing circuit which includes a solenoid device, including a solenoid plunger, and when the energizing circuit and the solenoid are deenergized the movable pilot valve member is disposed out of engagement with the pilot valve seat so that the oil or like hydraulic fluid will flow from the inlet port through the second branch of the auxiliary or pilot flow passage into the hydraulic flow control valve chamber at the opposite end thereof under a predetermined pressure such, for example, as 50 psi, so as to maintain the hydraulic fluid control valve member in the hydraulic flow control valve chamber in a state of balanced equilibrium and in a position to maintain the group of hydraulic flow control valve ports therein is closed position so that the main body of oil or like hydraulic flow from the fluid inlet port will flow from the inlet port around the hydraulic flow control valve chamber into the by-pass flow passage.
However, when the energizing circuit and the solenoid operating device for the movable pilot valve member are energized the pilot valve member is moved by the solenoid plunger toward or into engagement with the pilot valve seat, thereby reducing the volume of flow of hydraulic fluid through the second branch of the auxiliary or pilot flow passage into the hydraulic fluid control valve chamber with the result that a hydraulic pressure differential is established at opposite ends of the hydraulic fluid control valve member in the hydraulic fluid control valve chamber with the result that the pressure of the biasing spring on the hydraulic fluid control valve member is overcome and the hydraulic pressure of the hydraulic fluid at one end of the hydraulic fluid control valve member moves the hydraulic fluid control valve member into position to open the group of hydraulic fluid control ports and thus direct a proportional volume of the hydraulic fluid from the by-pass flow passage through the group of hydraulic fluid control valve ports into the hydraulic fluid control valve chamber and thence into regulated flow passage and to the regulated flow outlet port.
The invention also includes an electrical energizing circuit for the solenoid-operating device for the movable pilot valve member and a manually operable remote control device including a manually operable remote control lever for controlling the energization of the electrical energizing circuit and the operating solenoid for the pilot valve member so that the movement of the solenoid plunger which operates the movable pilot valve member bears a direct linear relation to the movement of the manually operable remote control lever and resulting energization of the electrical energizing circuit for the solenoid-operating device for the pilot valve with the result that the hydraulic pressure differential in the hydraulic fluid control valve chamber and the resulting linear movement of the hydraulic fluid control valve member therein and the corresponding extent to which the group of hydraulic fluid control valve ports is opened bears a direct linear relation to the extent of movement of the manually operable remote control lever from its normal or at rest position.
The invention further includes pressure-compensating means for compensating the hydraulic pressure in the regulated flow passage and in the by-pass flow passage so as to maintain a constant and uniform hydraulic pressure on the hydraulic fluid control valve member in the hydraulic fluid control valve chamber, and the new valve also embodies a reverse flow check valve unit for controlling the reverse flow of hydraulic fluid from the regulated flow passage outlet port through the regulated flow passage to the inlet port to establish a reverse flow through the regulated flow passage in certain uses of the invention.
In a typical use of the invention, the electrical energizing circuit for the operating solenoid for the movable pilot valve may incorporate one or more solenoid-operated hydraulic proportional flow control valves for use in hydraulic systems in which the invention may be used.
In another form of the invention the hydraulic fluid control valve member in the hydraulic fluid control valve chamber is normally disposed in a position in which the hydraulic fluid control valve ports therein conduct the main body or volume of oil or like hydraulic fluid from the inlet port through the hydraulic fluid control valve ports into the hydraulic fluid control valve chamber and thence into the regulated flow passage and energization of the operating solenoid for the movable pilot member causes the hydraulic fluid control valve member to be moved into position to direct a proportional part of the main body or volume from the inlet port into the by-pass flow passage and thence into the by-pass outlet port.